Selecting finger for crossbar switches



Jan. 13, 1948. R. A. SVENSSON El AL 2,434,373

SELECTING FINGER FOR CROSSBAR SWITCHES Filed Sept. 14, 1944 9w mm WW s Nu um. \J an an m 8 2m 8 mm E 2 v .Q 1 v Q i 7 P L. l E 8 a Q R la. I! m Y 2 2 2 3 Rm Q 2 E Q 2 RO\- Albin svtinsson Hans O\ov Patented Jan. 13, 1948 SELECTING FINGER FOR CROSSBAI? SWITCHES? Rolf Albin Syensson and H Q 0? seas de! Swisher 8 Application September 14, 1544, sesame. 553,967. In SWeden'Octobei' 25,1943

This invention relates to improvements in switching mechanisms and particularly in switches of the cross-bar type for use in establishing electrical connections.

It is the object of this invention to improve and simplify switches of this kind, to cheapen their assembly and adjustment and to cause them to perform their functions with greater accuracy and reliability.

Cross-bar switches to which the present invention may be applied are well known in" the art and consist essentially of contact setsarranged in horizontal and vertical rows and means 'including a group of horizontal operating members intersecting a group of vertical; operating members controlled by electromagnets. In'some type of switches the horizontal operating members are rotatable in two directions so that connections may be establishedv at either of two sets of contacts at an intersecting point by the rotation of an horizontal bar in one direction or'the other and the rotation of a vertical bar in one direction.

In such switches 'the rotation of a horizontal bar causes a selecting finger attached to said bar to be placed opposite an actuating springor opposite a contact operating card to select a set of contacts. When a vertical bar is operated, it causes this finger to be pressed against the actuating spring or against the contact operating card, which in turncause's a connection to" be established between the "contact sets at the corresponding cross-connecting point. The actuating springs operate chinsulatibnstuds or directly on a contact operating'cardplaced between one set of springs to'be actuated to close connections with the corresponding setof springs at the crossmomtsi Selecting fingers directly attached to a select bar show, however, a number of inconveniences. Fingers moved into a selecting position by aseleot bar and then held in said position by holding bars will resiliently'counter'act the return "of the corresponding select bar-to its normal position. This inconvenience will particularly be pronounced, when a plura'lity'of sets of actuated contacts are located in a row'corresponding to a single select bar. The power 'necessary to return the select bar's to normalpo'sition must therefore be dimensioned'to take care of such unfavourable cases, and which besides causes a considerable increase ofvthenumber of ampereturns needed to operate such a select'bar compared to that which otherwise might be'needed. Furthermore, the bars will in such'cases not entirely return to their normal. positions, which 1a Claims. (01. r s 27.54)

causes changes not desired in the pole distances ofthe select bar magnets and which causes"u'rire-' liability in the functioning of the device.

There wil l furth'erbe caused tensions not desired in selecting fingers held in' operating 'position;' when the corresponding select bar returns as normal posieodana these tensions will be still more" accentuated when the select bairotates in the "other direction. The selectin fingers on the first side will then be'bent 'in the form of an arch.

' Another disadvantage associated with known selecting fingers is the following." When a holding bar is deenerg'ised and'the corresponding selecting finger is released, said fingerbeing' un deifheavy bending tension obtains a tendency to widely oscillate so that the end of said finger may move to theopposite side and eventually be in operating position in front of another set of contact springs the moment when a holding magnet bar is operated,'in which case an erroneous onnect ons"es ab s It is a feature of the present invention to eliminate the above mentioned inconveniences, whereby instead of attaching the selecting fingers to'the select bars, said fingers are loosely and movably attached to the corresponding holdin g bar andarranged to be moved by a conveyer attached to the select bar upon actuation of the corresponding select bar at about right angles to the actuating movement of the corresponding holding bar, and to be disengaged from the said conveyer and select bar after actuation of the said holding bar.

In the cross-bar switch the holdin barand the selectingfingers are mounted on the armature of the electromagnet so that upon actuation of the armature the holding bar engages and holds a positioned selecting finger and simultaneously or afterthe actuation of the holding bar the corresponding finger is entirely disengaged from the conveyer fixed On the select bar.

From the above description it is understood that after each selection the select bar is unhampered to make new selections by means of other selecting fingers in the same row.

According to another feature of the invention there are provided hairpin-shaped units of two selecting fingers or wiresattached to the holding armature and projecting into proximity with two adjacent contact sets of movable contact springs, whereby the corresponding conveyer of the select bar is individual to the two shanks or prongs of the hairpin-shaped selecting wires, the tip of which conveyer is pointed and located between the two shanks so that the conveyer upon actuation of the select bar may laterally move one or the other shank into operating position.

According to still another feature of the invention there are provided individual guiding means on the holding bar and on the armature to guide each selecting finger in horizontal and in vertical direction in order to prevent vibrations and not desired movements outside the desired paths of the tips or ends of each finger, as otherwise upon actuation or release of the select bar or upon release of the holding bar the end of said selecting fingers might oscillate and cause false connections at the opposite set of contacts.

While the features of the invention may be realized by different embodiments the examples in the accompanying drawing serve to explain the invention, and in which drawing:

Fig. 1 shows a side view partly in section of part of a select bar and of a holding electroma net and bar of a cross-bar switch.

Fig. 2 shows a front View of the armature of the holding magnet and guiding means for the rear part of selecting fingers mounted thereon.

Fig. 3 shows a top view of the holding armature with five double hairpin-shaped selecting fingers and guiding means for the said fingers mounted thereon, and also a select bar with conveyer in normal position between two selecting fingers.

Fig. 4 is a rear view of the holding armature with holding bar and guiding means for the tips of the selecting fingers.

ig. 5 and Fig. 6 are parts of a front View partly in section of a select bar, a conveyer attached thereto and a hairpin-shaped unit of two selecting fingers in normal and operated positions respectively with respect to the conveyer and to the holding bar.

In Figs. 1-6 I are movable contact springs and 2 are stationary contacts or contact springs forming part of the same set or stack of contacts. 3 is contact operating means in the form of a common actuating insulation stud resting on an actuating spring provided with a specially shaped bend 5 to allow a bar I I attached to an extension 9 and the lugs ID of an armature 8 freely to enter a certain distance into the hollow part shaped by the bend 5, when a selecting finger is not in operating position. I2 is a thin plate with a bent part l3 attached to the bar II, in which plate there are provided holes 27-28 with a solid part 29 therebetween to serve as guiding means and as a stop respectively for the tips of the respective selecting fingers 20 and 2|, which form part of a hairpin-shaped unit 22-24 The individual shanks of said hairpin-shaped unit serve as selecting organ for two adjacent sets of contacts. The shanks are provided with loops 23, 24, respectively arranged to be guided by hooked projections E6 of a plate l5 attached to the extension 9 of the armature 8. The two shanks are at their rear part or at their hairpin-shaped union provided with a common bend 22, whereby the length of each shank can be prolonged in order to give sufficient elasticity to each shank. In front of each two rows of contacts there is provided a select bar I! rotatable in known manner by a selecting electromagnet in one or the other direction. Each select bar is provided with a hole [8 in front of the associated bend 22 and selecting fingers 29 and 2|. Attached to the select bar there is provided a conveyer [9 with a pointed tip 25 projecting between the two selecting fingers 20 and 2|.

Instead of using the actuating spring 4-5 and insulation stud 3, an actuating card can be used with the same advantage. Such a card is described in U. S. Patent No. 2,187,577 of January 16, 1940. Instead of using guiding holes 21-28 in a special plate l2 attached to the bar H these guiding holes can, of course, be provided in the bar'proper.

The device operates in the following manner. The shanks of the hairpin-shaped elastic and flexible selecting fingers, being introduced in rectangular holes 21 and 28 of the plate 12 on the holding bar H, are so adjusted that they are resiliently urged towards each other so that in normal position the shanks 20 and 2| are resting against the fixed parts or stops 29.

Normally the bar l2 enters the opening 5 in selecting spring 4 upon actuation of the armature 8, in which case no contact springs are operated. If, however, a selecting bar I1 is rotated in one direction, the conveyer 19 will move, for example, selecting finger 20 to the right in front of the opening 5 of an actuating spring 4. Upon actuation of the holding armature 8, the bar I2 cannot enter the opening 5 of spring 4 due to the fact that the selecting finger 20 is now located across said opening, whereby the spring 4 and the insulation stud 3 are displaced and the movable springs I of the corresponding group of contacts are brought in contact with stationary contacts 2, The shank 20 is now held in operating position by the bar II. When the select bar l7 and conveyer I!) return to their normal positions said conveyer is entirely disengaged from the selecting finger 20, which in no manner opposes the free movement of the bar 11. Into the openings 5 of other actuating springs 4, which correspond to other contact sets in the holding row, the bar, I2 can, however, enter, due to the fact that the other selecting fingers of the row have not been laterally moved.

Due to the fact that the rear parts of selecting fingers 20 and 2! and the frame 15 attached to the armature 8 are moved in such a direction upon actuation of the armature 8 that the rear part of the fingers are disengaged from the conveyer IS, an already selected finger of a certain select bar does not hamper a subsequent movement of the said select bar I! to move other selecting fingers by means of other conveyers IS on the same bar into the front of any of the two corresponding contact groups in other holding magnet rows.

The return of a selecting finger to its normal position takes place by its own spring action upon deenergization of the holding magnet.

The outstanding advantages of the present invention are the following. The selecting fingers are located in their respective normal positions on the armature of the holding magnet and closely follow the movements of the armature.

Due to the fact that the selecting fingers are not carried by or attached to the select bars as in known devices, the selecting fingers may be mounted in the shop in their respective places on the holding magnet armature and on the holding bar according to this invention. After the respective sets of contact rows have been mounted in a cross-bar switch frame, the holding magnets, the holding bars and already adjusted selecting fingers may be directly mounted in the frame in their predetermined positions, whereafter the select bars with their conveyers may finally be mounted in the frame.

By the present invention the heavy adjustment work of selecting fingers in known cross-bar switches is entirely eliminated. In known crossbar switches the select bars with their selecting fingers had to be mounted, whereafter the vertical and lateral positions of each selecting finger had to be adjusted. This work was very tedious and diificult to perform due to the fact that space between the diiierent parts of the cross-bar switch are very small.

If a selecting finger was deformed upon mounting or demounting a select bar, it was not easy to exchange such a deformed selecting finger.

Due to the fact that all selecting fingers according to the present invention are selfcontained removable units and by means of the guiding means are automatically and positively located in their respective normal positions, a unit of selecting fingers can easily be changed even without removing the corresponding holding armature or the corresponding select bar.

What we claim is:

1. In a switch, the combination with a plurality of normally open contact sets, a common holding bar, and means to reciprocate said holding bar between a contact release position and a contact actuating position, of a selecting finger for each contact set mounted on said contact bar for displacement relative thereto from a normal inoperative position in which it permits movement of said holding bar to its contact actuating position without closure of the associated set of contacts to an operative position in which it transmits the motion of said holding bar to its contact actuating position to the associated contact set to close the same, at least one rotatable contact select bar and an actuating member fixedly attached to said select bar and cooperating with said selecting finger when said holding bar is in its release position to displace said selecting finger from its inoperative to its operative position upon rotation of said select bar in one direction.

2. A combination, as claimed in claim 1, including means for disengaging said finger from said actuating member upon movement of said holding bar to its contact actuating position.

3. A combination, as claimed in claim 1, in which each actuating member cooperates with one selecting finger to shift the same to its operative position upon rotation of the associated select bar in one direction and with an adjacent selecting finger to shift the latter to its operative position upon rotation of said select bar in the opposite direction.

4. The combination, in a crossbar switch, of a plurality of sets of contacts, a rotatable select bar, a displaceable holding bar, a pair of selecting fingers mounted on said holding bar, each finger being movable relative to said holding bar from a normal inoperative position to an operative position to initiate the operation of an associated set of contacts, an actuating member fixedly attached to said select bar for engaging, upon rotation of said select bar in one or the other direction, one or the other of said fingers so as to shift it to its operative position independently of the not engaged finger, and means for displacing said holding bar to cause a selecting finger which has been previously shifted to its operative position to close said associated set of contacts and to hold said finger in said operative position, said fingers being arranged to be disengaged from said actuating member and select bar upon operation of said holding bar.

5. The combination in a crossbar switch of a plurality of sets of contacts, a rotatable select bar, a displaceable holding bar, a hairpin-shaped unit of two selecting fingers detachably mounted on said holding bar, each finger being movable relative to said holding bar from a normal inoperative position to an operative position to initiate the operation of an associated set of contacts, an actuating member fixedly attached to said select bar for engaging, upon rotation of said select bar in one or the other direction, one or the other of said fingers so as to shift it to its operative position independently of the not engaged finger, and means for displacing said holding bar to cause a selecting finger which has been previously shifted to its operative position to close said associated set or contacts and to hold said finger in its operative position.

6. A combination, as claimed in claim 5, in which said fingers are arranged to be disengaged from said actuating member and select bar upon operation of said holding bar.

7. A combination, as claimed in claim 5, in which said actuating member has a pointed tip normally positioned between the two selecting fingers forming the shanks of said hairpinshaped unit.

8. A combination, as claimed in claim 5, in which said holding bar is provided with guide means to receive the end of each selecting finger and to guide the same laterally into operating and back to normal positions in order to prevent vibrations of said ends upon operation or release of said holding bar.

9. A combination, as claimed in claim 5, in which said holding bar is provided with guide means to receive the end of each selecting finger and to guide the same laterally from normal into operating and back to normal positions, said guide means including a fixed part on said bar between the ends of the two fingers to prevent said ends from oscillating outside their respective predetermined paths upon actuation or release of the said holding bar.

10. A combination, as claimed in claim 5, in which each shank of said hairpin-shaped unit is provided with a loop, and said holding bar includes projections surrounded by said loops to guide lateral movements of th rear part of each shank adjacent the common bend uniting the shanks.

11. A combination, as claimed in claim 5, in which a substantial rear part of both shanks of each hairpin-shaped unit together with the common bend is bent at about right angles to the main portions of the shanks, in order to increase the length and flexibility of the shanks without increasing the size of the crossbar switch.

12. A combination, as claimed in claim 5, in which said select bar is provided with a hole in front of the rear part of the common bend of said hairpin-shaped unit, said hole being of such a size as to permit the hairpin-shaped unit of being freely removed and exchanged for a new unit without removing said select bar.

ROLF ALBIN SVENSSON. HANS oLo-v KARLs'rRoM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,166,764 Matthies July 18, 1939 2,118,935 Magrath May 31, 1938 2,113,215 Magrath Apr. 5, 1938 

